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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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The guest–host interactions in the H 2 O@C 60 and H 2 O@C 59 N endohedral fullerenes are probed by high-resolution photoelectron imaging.
The orientation of ellipsoidal cytochrome c molecules at the surface of silica nanoparticles was studied in a wide pH range by combining small-angle neutron scattering, adsorption measurements, and molecular dynamics simulations.
Polarized charges on dual-reactive centers of C 2 N-supported single-atom based transition metal ion catalysts promoting HCOOH dehydrogenation.
We study the physico-chemical properties and electrocatalytic activity towards oxygen reduction of two Fe–N–C catalysts based on carbide derived carbon.
Ultrafine β-Mo 2 C nanostructures encapsulated in N-doped carbon capsules featuring O–Mo–C interfaces as the active sites for HER have been unveiled.
Correction for ‘ThC 2 @C 82 versus Th@C 84 : unexpected formation of triangular thorium carbide cluster inside fullerenes’ by Yi Shen et al. , Chem. Sci. , 2022, https://doi.org/10.1039/d2sc04846a.
Dual Lewis acidic centers, CeO x and framework Sn, confined in Beta zeolite, catalyze the acetone C–C coupling followed by deoxygenation to isobutene, achieving a desirable product distribution and stability in the absence of water.
A single sorbent-catalytic (non-noble metal) material has been developed for the integrated direct air capture and catalytic conversion of captured CO 2 into C-C coupled products.
The Vera C. Rubin Observatory will produce an unprecedented astronomical data set for studies of the deep and dynamic universe. Its Legacy Survey of Space and Time (LSST) will image the entire southern sky every three to four days and produce tens of petabytes of raw image data and associated calibration data over the course of the experiment’s run. More than 20 terabytes of data must be stored every night, and annual campaigns to reprocess the entire dataset since the beginning of the survey will be conducted over ten years. The Production and Distributed Analysis (PanDA) system was evaluated by the Rubin Observatory Data Management team and selected to serve the Observatory’s needs due to its demonstrated scalability and flexibility over the years, for its Directed Acyclic Graph (DAG) support, its support for multi-site processing, and its highly scalable complex workflows via the intelligent Data Delivery Service (iDDS). PanDA is also being evaluated for prompt processing where data must be processed within 60 seconds after image capture. This paper will briefly describe the Rubin Data Management system and its Data Facilities (DFs). Finally, it will describe in depth the work performed in order to integrate the PanDA system with the Rubin Observatory to be able to run the Rubin Science Pipelines using PanDA.
Optical absorptance data, and a strong correlation between solar cell open circuit voltages and the ionization potentials of a wide range of differently substituted fullerene acceptors, are presented as empirical evidence for identical, or at least very similar, band gaps in all substituted C{sub 60} and C{sub 70} based fullerenes. Both the number and kind of substituents in this study are sufficiently varied to imply generality. While the band gaps of the fullerenes remain the same for all the different substitutions, their ionization potentials vary greatly in a span of more than 0.4 eV. The merits and drawbacks of using these results together with photoelectron based techniques to determine relative fullerene energy levels for, e.g., organic solar cell applications compared to more direct electrochemical methods are also discussed.
In both molecular and periodic solid-state systems there is a need for the accurate determination of the ionization potential and the electron affinity for systems ranging from light harvesting polymers and photocatalytic compounds to semiconductors. The development of a Green's function approach based on the coupled cluster (CC) formalism would be a valuable tool for addressing many properties involving many-body interactions along with their associated correlation functions. As a first step in this direction, we have developed an accurate and parallel efficient approach based on the equation of motion-CC technique. To demonstrate the high degree of accuracy and numerical efficiency of our approach we calculate the ionization potential and electron affinity for C{sub 60} and C{sub 70}. Accurate predictions for these molecules are well beyond traditional molecular scale studies. We compare our results with experiments and both quantum Monte Carlo and GW calculations.
Surface-pressure isotherms, X-ray reflectivity, and X-ray near-total reflection fluorescence were used to study the properties of 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C 61 (PCBM) that was pre-mixed with cesium carbonate and spread as a film at the air-water interface. The pre-mixed PCBM with cesium carbonate demonstrated a strikingly strong effect on the organization of the film. Whereas films formed from pure PCBM solution were rough due to strong inter-molecular interactions, the films formed from the mixture were much smoother. This indicates that the cesium carbonate moderates the inter-molecular interactions among PCBM molecules, hinting that the cesium diffusion observed in inverted organic photovoltaics and the likely ensuing ionic Cs-PCBM interaction decrease aggregation tendency of PCBM. As a result, this implies that the use of cesium salts affects the morphology of the organic layer and consequently improves the efficiency of these devices.
This work presents a detailed study of c-Si/Al{sub 2}O{sub 3} interfaces of ultrathin Al{sub 2}O{sub 3} layers deposited with atomic layer deposition (ALD), and capped with SiN{sub x} layers deposited with plasma-enhanced chemical vapor deposition. A special focus was the characterization of the fixed charge density of these dielectric stacks and the interface defect density as a function of the Al{sub 2}O{sub 3} layer thickness for different ALD Al{sub 2}O{sub 3} deposition processes (plasma-assisted ALD and thermal ALD) and different thermal post-deposition treatments. Based on theoretical calculations with the extended Shockley–Read–Hall model for surface recombination, these interface properties were found to explain well the experimentally determined surface recombination. Thus, these interface properties provide fundamental insights into to the passivation mechanisms of these Al{sub 2}O{sub 3}/SiN{sub x} stacks, a stack system highly relevant, particularly for high efficiency silicon solar cells. Based on these findings, it was also possible to improve the surface passivation quality of stacks with thermal ALD Al{sub 2}O{sub 3} by oxidizing the c-Si surface prior to the Al{sub 2}O{sub 3} deposition.
Following our previous study of prototypical insertion reactions of energetically asymmetric type with the RPMD (Ring-Polymer Molecular Dynamics) method [Y. Li, Y. Suleimanov, and H. Guo, J. Phys. Chem. Lett. 5, 700 (2014)], we extend it to two other prototypical insertion reactions with much less exothermicity (near thermoneutral), namely, X + H{sub 2} → HX + H where X = C({sup 1}D), S({sup 1}D), in order to assess the accuracy of this method for calculating thermal rate coefficients for this class of reactions. For both chemical reactions, RPMD displays remarkable accuracy and agreement with the previous quantum dynamic results that make it encouraging for the future application of the RPMD to other barrier-less, complex-forming reactions involving polyatomic reactants with any exothermicity.
The nucleon spin structure has been studied at Jefferson Lab’s Hall C in experiments RSS (E01-006) and SANE (E07-003), which measured double spin asymmetries using the U. of Virginia solid polarized target and CEBAF’s 6 GeV polarized electrons. The proton longitudinal spin structure g{sub 1} and transverse structure g{sub 2} have been investigated at kinematics extending from the elastic point to DIS, for four-momenta squared ranging from 0.8 to 5 GeV{sup 2}. The neutron structures have been measured in the region of the nucleon resonances at 1.3 GeV{sup 2} on a deuteron target. Results of both experiments will be highlighted. A brief survey of approved experiments for the 12 GeV program will also be presented.
Influence of temperature on the plasmonic field in the temperature range of 78–278 K was studied employing surface plasmon enhanced photoluminescence from the fullerene C{sub 60} thin film deposited on 2D array of Au nanoparticles. It was experimentally found that temperature dependence of plasmonic enhancement factor of C{sub 60} luminescence decreases monotonically with the temperature increase. Influence of temperature on plasmonic enhancement factor was found to be considerably stronger when the frequency of surface plasmon absorption band of Au nanoparticles and the frequency of fullerene luminescence band are in resonance. Electron-phonon scattering and thermal expansion of Au nanoparticles were considered as two competing physical mechanisms of the temperature dependence of plasmonic field magnitude. The calculations revealed significant prevalence of the electron-phonon scattering. The temperature induced increase in the scattering rate leads to higher plasmon damping that causes the decrease in the magnitude of plasmonic field.
Experiments in Alcator C-Mod to assess the level of toroidal asymmetry in divertor conditions resulting from poloidally and toroidally localized extrinsic impurity gas seeding show a weak toroidal peaking (∼1.1) in divertor electron temperatures for high-power enhanced D-alpha H-mode plasmas. This is in contrast to similar experiments in Ohmically heated L-mode plasmas, which showed a clear toroidal modulation in the divertor electron temperature. Modeling of these experiments using the 3D edge transport code EMC3-EIRENE [Y. Feng et al., J. Nucl. Mater. 241, 930 (1997)] qualitatively reproduces these trends, and indicates that the different response in the simulations is due to the ionization location of the injected nitrogen. Low electron temperatures in the private flux region (PFR) in L-mode result in a PFR plasma that is nearly transparent to neutral nitrogen, while in H-mode the impurities are ionized in close proximity to the injection location, with this latter case yielding a largely axisymmetric radiation pattern in the scrape-off-layer. The consequences for the ITER gas injection system are discussed. Quantitative agreement with the experiment is lacking in some areas, suggesting potential areas for improving the physics model in EMC3-EIRENE.
A design for a sample cell system suitable for high temperature Quasi-Elastic Neutron Scattering (QENS) experiments is presented. The apparatus was developed at the Spallation Neutron Source in Oak Ridge National Lab where it is currently in use. The design provides a special sample cell environment under controlled humid or dry gas flow over a wide range of temperature up to 950 °C. Using such a cell, chemical, dynamical, and physical changes can be studied in situ under various operating conditions. While the cell combined with portable automated gas environment system is especially useful for in situ studies of microscopic dynamics under operational conditions that are similar to those of solid oxide fuel cells, it can additionally be used to study a wide variety of materials, such as high temperature proton conductors. The cell can also be used in many different neutron experiments when a suitable sample holder material is selected. The sample cell system has recently been used to reveal fast dynamic processes in quasi-elastic neutron scattering experiments, which standard probes (such as electrochemical impedance spectroscopy) could not detect. In this work, we outline the design of the sample cell system and present results demonstrating its abilities in high temperature QENS experiments.